In the proposed study of the reactions of the flavoprotein, monamine oxidase, two techniques are to be used. The first method involving the use of a modelocked laser which generates picosecond pulses, is a preliminary work currently under way in our laboratory. This preliminary work is a study of the kinetics and intermediate electronic states of the flavin coenzyme as it participates in the reaction. The second proposed method involves the study of the excited triplet electronic state of flavin and flavoprotein molecules by means of phosphorescence microwave double resonance technique. The purpose is to use the double resonance technique to probe the interactions of the flavin coenzyme and the molecules surrounding the coenzyme. In this way, the intermediate enzyme-substrate complex can be studied without any chemical alterations at, or near, the active site, unlike the methods used by others in previous studies. The ultimate objective of this research is to help elucidate the mechanisms of flavoprotein reactions by spectroscopic observation of the riboflavin molecule as well as the amine substrate as they participate in the reaction process.